Switch



Nov. 24, 1942. w. H. FRANK E'IIAL- Filed July 11, 1940 INVENTORS. MM v4 ww BY .1 f

flZMLJMATTORNEY.

Patented Nov. 24, 1942 SWITCH William H. Frank and Lawrence E. Fisher, Detroit, Mich., assignors to Bulldog Electric Products Company, Detroit, Mich., a corporation of West Virginia Application July 11, 1940, Serial No. 344,888

7 Claims.

This application discloses a switch and parts thereof.

In a prior application, Serial No. 320,115, filed February 21, 1940, there is disclosed a switch having a front operated snap spring actuated rocker handle connected to a bail in turn detachably fastened to a plurality of movable switching heads. This application relates to that type of switch, and it is understood that although the disclosure hereof is restricted to the improvements hereof over such switch, that the entire switch is considered as disclosed herein, being incorporated, by reference to th disclosure of application Serial No. 320,115.

An object is to provide a novel switching head for switches of the character described, such as is shown in the appended drawing. In the drawing, Figs. 1 and 2 show a roller type movable contact construction for a switching head.

A switch of the character under consideration comprises a sheet metal box having a springy back on which is resiliently mounted an insulating base ll equipped with stationary contact prongs 12 over which telescope the movable contact heads l3. These have in them movable contacts which electrically interconnect the prongs when they are moved as far as possible towards the box back by the operating bail H which is shown as removably received within open sided hooks l8 connected to the forward ends of the heads.

A handle and an overcenter spring are provided for operating the bail, and although such parts are not specifically shown, they are considered as incorporated by reference.

Each movable contact head may include an insulation housing 3| provided with cel1 '32 between which is a barrier 33.

In the contact head of Figs. 1-2, the barrier mounts an outside contact 34 for embracing the prongs l2 and an inside contact 35 for fitting between them. The inside contact of Figs. -2 comprises a pair of copper rollers. The outside contact 34, instead of being of the same material as the copper inside contact 35 is of spring steel and is shown as being so formed that the inside contact provides an arcing tip for the strip. Thus, on contact operation, the electrical are formed, if any, magnetically attracted to steel, is stretched out more than would be the case if the strip 34 were of copper to which material an arc is not naturally attracted. A tendency for the arc to stretch out, where it can dissipate quickly, has been found helpful to attain the result of an extremely unstable and quickly dissipated arc.

The prongs l2 have their ends bevelled, as seen at 36, so that the spring 34 may bias the prongs towards each other during switch closing to put great pressure on rollers 35, but without excessive friction on switch closing movement.

The bevels 36 help the handle and spring of the switch on switch opening movement, and the wedging action does not excessively impede switch closing movement, because of the momentum of the parts. The bail, being biased downward by the switch spring, prevents the bevels 36 from wedging the switch open when it is closed.

When the switch handle is moved to circuit closing position, there is little resistance to circuit closing movement until spring 34 wedges itself well onto bevels 36, long after rollers 35 have reached the prongs. Such movement terminates when the momentum of the parts on such movement is equalized by the pressure created by the engagement at 34-45, and that pressure helps establish and maintain contact pressure in closed circuit, with a minimum of direct force applied at the handle.

However, when the handle is pushed for open circuit movement, the energy stored in spring 34 and in the prongs I2 which are compressed by that spring, tends to help efiect contact separation, thus easing the burden of separating con tacts.

When the construction hereof is utilized in multipole, as in a multipole switch, the variations in contact alinement which might be detrimental to the operation and action just described, are compensated for by the springiness or resiliency intentionally provided in the box back, permitting the bases to float somewhat and thus align, themselves to the springs of the heads and actuating mechanism.

Now having described the switch heads hereof, reference should be had to the claims hereof which point out and distinctly define the invention.

We claim:

1. A switch having a back from which forwardly project spaced stationary contacts, a movable contact mounted to move rectilinearly towards and away from said back for engaging or leaving said stationary contacts, the movable contact being mounted on, so as to be guided by, the stationary contacts in its motion, the stationary contacts being formed as forwardly projecting prongs, the movable contact consisting of two parts, engaging opposite sides of the stationary contacts, with one part being a flexible strap embracing the stationary contacts and the other part fitting between them, the latter part comprising two parallel rollers, arranged to follow each other as they move towards and away from the prongs, with the one nearer the prongs being of smaller diameter than the other.

2. A switch having a back from which forwardly projects a stationary contact, a movable contact mounted to move rectilinearly towards and away from said back for engaging or leaving said stationary contact, the movable contact being mounted on, so as to be guided by, the stationary contact in its motion, the stationary contact being formed as a pair of forwardly projecting prongs, the movable contact consisting of two parts, engaging facing surfaces of the prongs, and a spring for biasing the two parts of the movable contact towards and against the prongs, one of the parts of the movable contact fitting between the prongs and comprising two parallel rollers, arranged to follow each other as they move towards and away from the prongs, with the one nearer the prongs being of smaller diameter than the other.

3. A switch having a back from which for wardly projects a stationary contact, a movable contact mounted to move rectilinearly towards and away from said back for engaging or leaving said stationary contact, the stationary contact consisting of two forwardly projecting prongs, and the movable contact being mounted on, so as to be guided by, the stationary contact in its motion, the movable contact having a spring strap embracing the prongs to bias them towards each other, the free ends of the prongs, on their outer surfaces, being bevelled to cooperate with the ends of the strap and provide a wedging action between the strap and the prongs, one of the parts of the movable contact fitting between the prongs and comprising two parallel rollers, arranged to follow each other as they move towards and away from the prongs, with the one nearer the prongs being of smaller diameter than the other.

4. In a switch, a contact set consisting of two stationary parallel prongs and a movable contact mounted on, so as to be guided by, the stationary contact in its motion and comprising two parts, one adapted to fit between and engage the facing surfaces of the prongs and comprising two parallel rollers, arranged to follow each other as they move towards and away from the prongs, with the one nearer the prongs being of smaller diameter than the other and the other adapted to embrace the prongs, engaging them on their outsides, with the latter part of the movable contact comprising a flexible strap.

5. A switch comprising a box having a back from which forwardly projects a stationary contact, a movable contact mounted to move rec-i tilinearly towards and away from said back for engaging or leaving said stationary contact, the

stationary contact consisting of two parallel forwardly projecting prongs, and the movable contact being mounted on, so as to be guided by, the stationary contact in its motion and comprising two parts, one adapted to fit between and engage the facing surfaces of the prongs and the other adapted to embrace the prongs, engaging them on their outsides, with the latter part of the movable contact comprising a flexible strap, the former part comprising a roller arranged to roll between and engage the facing prong surfaces, the free ends of the prongs, on their outer surfaces, being bevelled to cooperate with the ends of the strap and provide a wedging action between the strap and the prongs.

6. In a switch, a contact set comprising a pair of parallel spaced prongs, and a movable contact for bridging them, the latter comprising two parallel rollers arranged to fit between them, with each roller engaging both prongs, the roller nearer the prongs being of smaller diameter than the other.

'7. In a switch, a contact set comprising a pair of parallel spaced prongs, and a movable contact for bridging them, the latter comprising two parallel rollers arranged to fit between them, with each roller engaging both prongs, the roller nearer the prongs being of smaller diameter than the other, and a flexible strap to embrace the prongs.

WILLIAM H. FRANK. LAWRENCE E. FISHER. 

